I've bought one, a bank partially owned by some family friends. I bought in the initial offering and then re-upped a few years later when they did a rights offering. Kept the position small, since it is very illiquid and somewhat speculative.
The bank itself has executed reasonably well on their plan. They need to make some money, but the real juice is in opening branches and building up a deposit base. They have been squeezed a bit by the inverted yeld curve like most retail banks, but still do OK. No dividends and I don't expect any. I imagine that some day they will sell out to a larger competitor, but since they are still opening branches I think it will be a while.
Many of these guys do not file SEC statements, so you have to go to FDIC: Federal Deposit Insurance Corporation
if you want financials to look at. Make sure you are comfy with the insiders and the business strategy before you buy, since you will have little protection (aside from banking regulators) and little liquidity. My bank is listed OTC (SHRC), but trades rarely and strangely.
Frankly, there are so many large, established institutions selling at decade lows right now, I would just buy a quality larger bank that is exchange listed, unless you have some special reason to do otherwise.